DITCH AND OBSTRUCTION DETECTION SYSTEM FOR MOTOR VEHICLES

Abstract

The disclosure relates to a method and an associated device for detecting uneven surfaces in vehicle environments. The method comprises emitting a first ultrasonic pulse or first ultrasonic burst and emitting a second ultrasonic pulse or second ultrasonic burst, and receiving a first reflection signal of the first ultrasonic pulse or a first reflection signal of the first ultrasonic burst and receiving a second reflection signal of the second ultrasonic pulse or a second reflection signal of the second ultrasonic burst. In the further course of the method, a comparison is made of the first reflection signal with the second reflection signal, and the presence of a surface unevenness in the vehicle's environment, or the presence of a surface curvature in the vehicle's environment, is determined.

Claims

1.-10. (canceled)

11. A method comprising: emitting a first ultrasonic signal; emitting a second ultrasonic signal; receiving a first reflection signal of the first ultrasonic signal; receiving a second reflection signal of the second ultrasonic signal; comparing the first reflection signal with the second reflection signal; and determining at least one of a presence of a surface unevenness in the vehicle environment or a presence of a surface curvature in the vehicle environment based on the comparison.

12. The method according to claim 11 wherein the first ultrasonic signal includes a first ultrasonic pulse or a first ultrasonic burst, and the second ultrasonic signal includes a second ultrasonic pulse or a second ultrasonic burst.

13. The method according to claim 11 wherein comparing the first reflection signal with the second reflection signal and determining the at least one of the presence of the surface unevenness or the presence of the surface curvature in the vehicle's environment comprises: executing a cross-correlation between a first temporal segment of the first reflection signal and a second temporal segment of the second reflection signal, wherein the cross-correlation can be preceded by a scaling of the first temporal segment of the first reflection signal and a scaling of the second temporal segment of the second reflection signal, and wherein a cross-correlation signal is obtained from the cross-correlation.

14. The method according to claim 13 wherein comparing the first reflection signal with the second reflection signal and determining the presence of the surface unevenness in the vehicle environment or the presence of the surface curvature in the vehicle's environment comprises: comparing an amplitude of the cross-correlation signal with a threshold value; determining a point in time at which the amplitude of the cross-correlation signal exceeds the threshold value; determining the presence of the surface unevenness or the presence of the surface curvature when the point in time is prior to an earliest permitted point in time, or when the point in time is after a latest permitted point in time, or when the threshold value is not exceeded.

15. The method according to claim 11 wherein at least one reflection signal is multiplied by a gate signal prior to obtaining the cross-correlation signal.

16. The method according to claim 11 wherein the surface unevenness that is to be detected includes at least one of a pothole or a rock or a parking boundary, or a step, or a ledge or a landing.

17. A method for detecting a surface unevenness in a vehicle environment, comprising: emitting a first ultrasonic signal; emitting a second ultrasonic signal; receiving a reflection of the first ultrasonic signal at a first point in time; receiving a reflection of the second ultrasonic signal at a second point in time; comparing the first point in time with a first time window that begins and ends after emitting the first ultrasonic signal; comparing the second point in time with a second time window that begins and ends after emitting the second ultrasonic signal; determining a presence of a flat surface in the vehicle environment when the first point in time lies within the first time window, and the second point in time lies within the second time window; determining a presence of a relevant negative surface unevenness in the vehicle environment when the first point in time lies within the first time window and the second point in time lies temporally after a temporal end of the second time window, or when no second point in time could be determined; or when the first point in time lies temporally after a temporal end of the first time window, and the second point in time lies temporally after the temporal end of the second time window, or when no second point in time could be determined; determining a presence of a relevant positive surface unevenness in the vehicle environment, when the first point in time lies within the first time window and the second point in time lies temporally prior to the temporal beginning of the second time window; or when the first point in time lies temporally prior to the temporal beginning of the first time window and the second point in time lies temporally prior to the temporal beginning of the second time window.

18. The method according to claim 17 wherein the first ultrasonic signal includes a first ultrasonic pulse or a first ultrasonic burst, and the second ultrasonic signal includes a second ultrasonic pulse or a second ultrasonic burst.

19. The method according to claim 17, wherein emitting of the first ultrasonic signal takes place in a form of a first ultrasonic beam, and wherein emitting of the second ultrasonic signal takes place in a form of a second ultrasonic beam, and wherein the first ultrasonic beam is oriented such that, if a surface to be measured is flat, the first ultrasonic beam strikes the surface to be measured at a first distance, at a first point of impact, and wherein the second ultrasonic beam is oriented such that, if the surface to be measured is flat, the second ultrasonic beam strikes the surface to be measured at a second distance, at a second point of impact, and wherein, if the surface to be measured is flat, the first distance between the first point of impact (AP1) and a first ultrasound sensor is less than the second distance between the second point of impact and a second ultrasound sensor.

20. The method according to claim 17, wherein the surface unevenness to be detected is a pothole or a rock or a parking boundary or a step or a ledge or a landing.

21. A device for detecting a surface unevenness or a surface curvature in a vehicle environment, comprising a first ultrasound sensor; a second ultrasound sensor; an analyzer; wherein the first ultrasound sensor emits a first ultrasonic beam, and wherein the second ultrasound sensor emits a second ultrasonic beam, and wherein the first ultrasound sensor receives a reflection of the first ultrasonic beam, and wherein the second ultrasound sensor receives a reflection of the second ultrasonic beam, and wherein the first ultrasound sensor converts the received reflection of the first ultrasonic beam into a first reflection signal, and wherein the second ultrasound sensor converts the received reflection of the second ultrasonic beam into a second reflection signal, and wherein the first ultrasonic beam is oriented such that if a surface to be measured is flat, the first ultrasonic beam strikes surface to be measured at a first distance, at a first point of impact, and wherein the second ultrasonic beam is oriented such that if the surface to be measured is flat, the second ultrasonic beam strikes the surface surface to be measured at a second distance, at a second point of impact, and wherein, in a case the surface to be measured is flat, the first distance between the first point of impact and the first ultrasound sensor is less than the second distance between the second point of impact and the second ultrasound sensor, and wherein the first ultrasound sensor receives the first reflection of the first ultrasonic beam at a first point in time after emitting the first ultrasonic beam, and wherein the second ultrasound sensor receives the reflection of the second ultrasonic beam at a second point in time after emitting the second ultrasonic beam, and wherein the analyzer compares the first point in time with a first time window, which begins at a first starting time, which lies after emitting the first ultrasonic beam, and ends at a first ending time after the first starting time, and wherein the analyzer indicates a flat surface when the first point in time lies within the first time window and the second point in time lies with the second time window, or indicates a relevant negative surface unevenness or a downward surface curvature when the first point in time lies within the first time window, and the second point in time is temporally after a temporal end of the second time window, or when no second point in time could be determined, or indicates the relevant negative surface unevenness or the downward surface curvature when the first point in time lies temporally after the first ending time of the first time window, and the second point in time lies temporally after the temporal end of the second time window, or when no second point in time could be determined, or indicates a relevant positive surface unevenness or an upward surface curvature when the first point in time lies within a first time window, and the second point in time lies temporally prior to the temporal start of the second time window, or indicates the relevant positive surface unevenness or the upward surface curvature when the first point in time lies temporally prior to the first starting time and the second point in time lies temporally prior to the temporal start of the second time window.

22. The device according to claim 21, wherein the surface unevenness to be determined includes at least one of a pothole or a rock or a parking boundary or a step or a ledge or a landing.

Description

DESCRIPTION OF THE FIGURES

[0018] FIG. 1 shows the rear of an exemplary motor vehicle. A first ultrasound sensor (S1) emits a first ultrasound signal (US1) toward the surface (B) over a short distance (d1). A second ultrasound sensor (S2) emits a second ultrasound signal (US2) toward the surface (B) over a longer distance (d2). The first ultrasound signal (US1) strikes the surface (B) at a first point of impact (AP1). The second ultrasound signal (US2) strikes the surface (B) at a second point of impact (AP2). Because the second distance (d2) is greater than the first distance (d1), the first ultrasound signal (US1) requires less time to travel the distance from the first ultrasound sensor (S1) to the first point of impact (AP1) and back to the first ultrasound sensor (S1). The first ultrasound sensor (S1) receives the reflection of the first ultrasound signal (US1) against the surface (B) at the first point of impact (AP1). The second ultrasound sensor (S2) receives the reflection of the second ultrasound signal (US2) against the surface (B) at the second point of impact (AP2) in the same manner.

[0019] FIG. 2 shows, schematically, the reflected ultrasound signals (US1, US2) received by the ultrasound sensors (S1, S2) after reflection and reception thereof. FIG. 2a shows, schematically, the received signal of the first ultrasound sensor (S1) with the reflection of the first ultrasound signal (ES). FIG. 2b shows, schematically, the received signal of the second ultrasound sensor (S2) with the reflection of the second ultrasound signal (FB). The curve indicated by FB represents the temporal position of the reflection pulse with a flat surface (B). The curve indicated by AS schematically represents the exemplary temporal position of the reflection pulse when the surface rises, when there is a stone in the pathway, or there is a step or a landing located in the pathway. The curve indicated by AF represents the exemplary temporal position of the reflection pulse when the surface (B) dips, or there is a pothole or ditch located in the pathway, or a downward step or a downward ledge located in the pathway. The origins in the drawings in FIGS. 2a and 2b are selected as the respective point in time of emitting the respective ultrasound signals (US1, US2) and an equivalent temporal scale is also selected. The temporal delay between the curve (ES) of the received signal of the first ultrasound sensor (S1) with the reflection of the first ultrasound signal and the curve (FB) representing the temporal position of the reflection pulse with a flat surface (B), represents the temporal reference value for deciding whether the surface dips or rises. If the rise is greater than a predefined rise threshold value, a first alarm can be triggered. If the dip is greater than a predefined dip threshold value, a second alarm can be triggered.